A lot of people on here like the 5100's and have had good experiences with them in terms of longevity for normal use and light off-roading. Plus they're cheap, ride smooth, and have a lifetime warranty. They're just not made for the abuse I was dishing out. I was probably doing about 35-45 mph when the started to spew out hot stinky oil. Sucked too, because we still had to tow our camper all the way back to LA.
I installed them myself and reinstalled them again when I killed them in the first 3 months. In fact, within 6 months I broke the second set as well. After that I decided that I was done wasting time with shocks that couldn't handle what I wanted to do, so I got the Fox's, which have been awesome. Better ride quality, durability, and easier to install than the billies, but they're very expensive. If you plan to off road hard and fast and have the cash go with something beefier, Fox, Icon, and King are all supposedly great. I can only vouch for the Fox's. Check out TAP auto. Last I checked they carried Fox's, Kings, and billies. I think they still have the "titantalk" coupon code too.